System and method of forming an injection-bonded joint

ABSTRACT

A method of forming an injection-bonded joint may include forming a chamber wall within a bondline region between mating surfaces of a first part and a second part. The chamber wall may divide a bondline length and define at least one adhesive chamber. The method may include injecting a structural adhesive into the adhesive chamber through an injection port, and discharging excess adhesive from the adhesive chamber through a bleed hole.

FIELD

The present disclosure relates generally to structural joints and, moreparticularly, to adhesively bonded joints of relatively long length.

BACKGROUND

Bonded joints are typically formed by applying a layer of adhesive tothe mating surfaces of one or more parts to be joined. The parts arethen brought together and held in position relative to one another whileallowing the adhesive in the bondline to cure. For example, when bondingan end ring having a C-channel cross-section to an edge of a cylinder,the end ring may be oriented such that the C-channel is facing upwardly.A pool of adhesive may be installed within the C-channel and thecylinder edge may be lowered down into the C-channel. The adhesive mayspill out of the C-channel until the cylinder edge contacts the bottomof the C-channel. The cylinder and the end ring may be held in positionwhile the adhesive cures.

Unfortunately, the above-noted process may produce less-than-desirableresults in the final bonded joint between the end ring and the cylinder.In this regard, the relatively long length of the bondline extendingaround the cylinder circumference may result in unpredictability withregard to the flow of adhesive in the C-channel as the cylinder islowered into the end ring. For example, the long length bondline mayaffect the ability of the adhesive to flow from the bottom of theC-channel to the top edge of the C-channel at all locations around thecylinder circumference as the cylinder edge is lowered into theC-channel.

Such unpredictability with regard to adhesive flow may result inreworking the bonded joint to bring the bonded joint to within designtolerances. In cases where repair of the bonded joint is not possible,it may be necessary to scrap the bonded parts and assemble a replacementwhich may have a detrimental impact on cost and schedule. Theunpredictability associated with adhesive flow may also require theinstallation of anti-peel fasteners along the bondline to preventpeeling of the bonded joint at the edges of the bondline. Unfortunately,the installation of anti-peel fasteners may add to the cost, complexity,and weight of the structural assembly.

As can be seen, there exists a need in the art for a system and methodof forming a bonded joint that provides a means for controlling the flowof adhesive within the bondline during the bonding process. In thisregard, there exists a need in the art for a system and method offorming a bonded joint that provides predictability with regard to theflow of adhesive in long length bondlines.

SUMMARY

The above-noted needs associated with bonded joints are specificallyaddressed and alleviated by the present disclosure which provides amethod of forming an injection-bonded joint. The method may includeforming a chamber wall within a bondline region between mating surfacesof a first part and a second part. The chamber wall may divide abondline length and defining at least one adhesive chamber. The methodmay additionally include injecting a structural adhesive into theadhesive chamber through an injection port, and discharging excessadhesive from the adhesive chamber through a bleed hole.

In a further embodiment, disclosed is a method of forming aninjection-bonded joint including the step of forming a series of chamberwalls within a bondline region between mating surfaces of a first partand a second part. The chamber walls may divide the bondline length intoa plurality of adhesive chambers. The method may additionally includeforming bondline dams along a part edge of at least one of the firstpart and the second part. The chamber walls, the bondline dams, and themating surfaces may collectively enclose the adhesive chambers. Themethod may further include injecting a structural adhesive into theadhesive chambers through an injection port formed in one of the firstpart and the second part, discharging excess adhesive from the adhesivechambers through at least one bleed hole, and collecting the excessadhesive in adhesive reservoirs fluidly coupled to the bleed holes.

Also disclosed is a structural assembly made up of a first part and asecond part. The first part and the second part may have mating surfacesthat may be adhesively bonded together along a bondline region having abondline length. The structural assembly may include a series of chamberwalls formed along the bondline length and dividing the bondline lengthinto a plurality of adhesive chambers. The structural assembly mayinclude a structural adhesive injected into the adhesive chambersthrough at least one injection port to bond the first part to the secondpart.

The features, functions and advantages that have been discussed can beachieved independently in various embodiments of the present disclosureor may be combined in yet other embodiments, further details of whichcan be seen with reference to the following description and drawingsbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the present disclosure will become moreapparent upon reference to the drawings wherein like numbers refer tolike parts throughout and wherein:

FIG. 1 is a cross-sectional illustration of a spacecraft encapsulatedwithin a launch vehicle;

FIG. 2 is a perspective illustration of an embodiment of a structuralassembly for supporting the spacecraft of FIG. 1 and comprising astructural cylinder having an internal ring, an external ring, and apair of end rings with C-channel cross-sections bonded to a structuralcylinder;

FIG. 3 is a cross-sectional illustration of the end ring taken alongline 3 of FIG. 2 and illustrating a bonded joint between the C-channelcross-section and the cylinder edge of the cylinder;

FIG. 4 is a flat pattern layout of the bonded joint between the matingsurfaces of the end ring and the cylinder and illustrating therelatively long bondline length of the bondline region at the bondlinejoint;

FIG. 5 is an exploded perspective diagrammatic illustration of a portionof an embodiment of a bonded joint and illustrating a pair of bond wiresmountable against the cylinder edge prior to inserting the cylinder edgeinto the C-channel;

FIG. 6 is a perspective schematic illustration of the bonded joint ofFIG. 5 showing a pairs of shims temporarily installed on opposite sidesof the bond wires to assist in forming the chamber walls dividing thebondline length;

FIG. 7 is a perspective schematic illustration of the bonded joint ofFIG. 6 showing a bondline dam installed along a channel edge of theC-channel and further illustrating bleed holes formed as openings in thebondline dam;

FIG. 8 is a perspective schematic illustration of the bonded joint ofFIG. 7 showing an embodiment of an adhesive reservoir configured as ashelf and positioned along the channel edge;

FIG. 9 is a perspective schematic illustration of the bonded joint ofFIG. 7 showing adhesive reservoirs configured as vertical columnsfluidly coupled to the bleed holes;

FIG. 10 is a side schematic illustration of the bonded joint of FIG. 9in an embodiment having a large bleed and a small bleed hole positionedon opposite sides of the chamber walls;

FIG. 11 is a side schematic illustration of the bonded joint of FIG. 10and showing the injection of structural adhesive into the adhesivechamber defined by the chamber walls and illustrating the flow directionof the structural adhesive and air bubbles within the adhesive chamber;

FIG. 12 is a side schematic illustration of the bonded joint of FIG. 11and showing the flow of structural adhesive and air bubbles toward thelarge bleed hole and the discharge of excess adhesive resin through thesmall bleed hole and into the adhesive reservoir;

FIG. 13 is a cross-sectional illustration of the bonded joint takenalong line 13 of FIG. 12 and showing the flow direction of structuraladhesive through gaps between the cylinder edge and the C-channel;

FIG. 14 is a side schematic illustration of the bonded joint of FIG. 11and showing the adhesive chamber in a filled state with excess adhesivecontained in the adhesive reservoirs on opposite sides of the centeradhesive chamber;

FIG. 15 is a side schematic illustration of the bonded joint of FIG. 14and showing the injection of the structural adhesive into the pluralityof adhesive chambers;

FIG. 16 is a cross-sectional illustration of the bonded joint takenalong line 16 of FIG. 15 and illustrating a plug for plugging theinjection port after filling the adhesive chamber with structuraladhesive;

FIG. 17 is a side schematic illustration of the bonded joint of FIG. 15and showing each one of the adhesive chambers filled with structuraladhesive and further showing excess adhesive contained within theadhesive reservoirs;

FIG. 18 is a side schematic illustration of the bonded joint of FIG. 17in a final state following the removal of the adhesive reservoirs andthe bondline dams, and further illustrating the optional installation ofmechanical fasteners through each one of the adhesive chambers;

FIG. 19 is a cross-sectional illustration of the structural cylindertaken along line 19 of FIG. 2 and illustrating an embodiment of a bondedjoint between an external ring and the cylinder;

FIG. 20 is a flat pattern layout of the bonded joint of FIG. 19illustrating the injection of structural adhesive into an injection portlocated at an approximate geometric center of the adhesive chamber;

FIG. 21 is a cross-sectional illustration of the bonded joint takenalong line 21 of FIG. 20 and illustrating the injection of structuraladhesive into the adhesive chamber;

FIG. 22 is a side schematic illustration of the bonded joint of FIG. 20in a final state following the removal of the adhesive reservoirs andthe bondline dams, and further illustrating the optional installation ofmechanical fasteners through each one of the adhesive chambers;

FIG. 23 is an illustration of a flow chart of a method of forming aninjection-bonded joint;

FIG. 24 is a block diagram of a bonded joint;

FIG. 25 is a flow diagram illustrating an aircraft manufacturing andservice methodology; and

FIG. 26 is a block diagram of an aircraft.

DETAILED DESCRIPTION

Referring now to the drawings wherein the showings are for purposes ofillustrating preferred and various embodiments of the disclosure, shownin FIG. 1 is a sectional illustration of spacecraft 102 encapsulatedwithin a launch vehicle 100. The spacecraft 102 may be supported on acentral core structural assembly 104 having a cylindrical configurationand extending vertically through the center of the spacecraft 102.

FIG. 2 illustrates an embodiment of the cylindrical structural assembly104. The structural assembly 104 may include a cylinder 110 which may beformed of fiber-reinforced polymer matrix material 124 although thecylinder 110 may be formed of metallic material (not shown) or acombination of composite material and metallic material and/or othermaterials. The structural assembly 104 may additionally include one ormore rings 130, 170, 172 that may be bonded to the cylinder 110 toincrease the strength of the cylinder 110 and/or accommodate localizedloads and/or interface loads at locations where the cylinder 110attaches to mating components (not shown) such as at an interface (notshown) between the launch vehicle 100 (FIG. 1) and the spacecraft 102(FIG. 1). In the embodiment shown, the rings may include an internalring 170, an external ring 172, and a pair of end rings 130.

Advantageously, in FIG. 2, the rings 130, 170, 172 are adhesively bondedto the cylinder 110 using an injection-bonding method disclosed hereinwhich provides a means for bonding the rings 130, 170, 172 to thecylinder 110 with a significant increase in the quality and consistencyof the bond joints 106 relative to conventionally-bonded joints. Theinjection bonding method disclosed herein advantageously includesadhesive chambers 210 formed in a bondline region 300 between the matingsurfaces 192, 194 of the mated parts. The adhesive chambers 210 may beprovided by constructing a series of chamber walls 212 within thebondline region 300. The chamber walls 212 may be spaced apart from oneanother along the bondline length 306 to break up the bondline length306 into short, defined, adhesive chambers 210. The chamber walls 212may be spaced apart from one another at a substantially equal spacing224 from one another, or the chamber walls 212 may be spaced apart fromone another at unequal spacings (not shown). Structural adhesive 370 maybe injected into each one of the adhesive chambers 210 in a controlledmanner and the structural adhesive 370 may be allowed to cure.

As described in greater detail below, in FIG. 2, by breaking up thebondline length 306 and controlling the flow of structural adhesive 370within the short, defined segment of each adhesive chamber 210, thestructural adhesive 370 may fill each adhesive chamber 210 by rising tothe top (not shown) of the adhesive chamber 210 and staying there untila substantial entirety of the adhesive chamber 210 is filled withstructural adhesive 370. In this manner, the potential for theoccurrence of voids (not shown) or air bubbles (not shown) along thebondline perimeter 302 such as along the top edge (not shown) of theadhesive chamber 210 may be significantly reduced or eliminated. Thereduction or elimination of voids (not shown) and air bubbles (notshown) at high-stress locations (not shown) along the bondline perimeter302 (FIG. 3) may result in an increase in the overall strength anddurability of the bonded joint 106 relative to conventionally-bondedjoints.

In FIG. 2, the bonding method is specifically advantageous forrelatively long length geometry features 108 which may be characterizedas bondline regions 300 having a long bondline length 306 relative tothe bondline width 308. For example, in the context of the cylindricalstructural assembly 104 illustrated in FIG. 2, the relatively longlength geometry feature 108 may be represented by the long distancearound the cylinder circumference 112 relative to the short bondlinewidth 308. Advantageously, the presently-disclosed bonding method allowsfor the elimination of bolts (not shown) or other mechanical fastenersin the cylindrical bonded joints 106 which provides significantadvantages over conventionally-bonded joints (not shown) in cylindricalstructures that require mechanical fasteners (not shown) to achieve therequired strength and durability in such conventionally-bonded joints.In this regard, the presently-disclosed method provides a means forforming high-strength, high-durability bonded joints 106 in cylindricalstructural assemblies 104 with no mechanical fasteners and resulting insignificant weight savings relative to conventional bonded/mechanicallyfastened cylindrical joints.

In FIG. 2, the adhesive chambers 210 may additionally provide increasedflexibility with regard to the amount of time available for completing abonded joint 106 within the pot life of the structural adhesive 370. Forexample, in an embodiment, a portion of the adhesive chambers 210 in abondline region 300 may be filled with structural adhesive 370 andallowed to cure. Remaining portions of the adhesive chambers 210 of thebondline may then be filled and allowed to cure during one or moresubsequent bonding operations. In the context of the cylindricalstructural assembly 104 shown in FIG. 2, the effect of the injectionbonding method disclosed herein is an elimination of the mass penaltyotherwise associated with attachment of the rings 130, 170, 172 to thecylinder 110 using mechanical fasteners (not shown). The elimination ofthe mass penalty translates into a reduction in the structural mass ofthe spacecraft 102. The reduction in spacecraft 102 structural mass mayallow for an increase in the amount of fuel (not shown) carried by thespacecraft for the attitude control system (not shown) which may resultin an increase in the operational life of the spacecraft 102.

Although the bonding method disclosed herein is described in the contextof a cylindrical structural assembly 104 (FIG. 2) for a spacecraft 102(FIG. 1), the bonding method may be implemented in any one of a varietyof different applications and in any one of a variety of differentindustries. For example, the bonding method may be implemented incommercial, civil, and military applications. Furthermore, the bondingmethod may be incorporated into a wide variety of platforms including,but not limited to, marine, automotive, aircraft, and/or spaceplatforms. In this regard, the bonding method may be incorporated intoany vehicular system or non-vehicular system, without limitation.

In FIG. 3, shown is a cross-sectional illustration of an embodiment of abonded joint 106 between a first part 190 and a second part 196 havingmating surfaces 192, 198 adhesively bonded together. In FIG. 3, thefirst part 190 comprises a cylinder 110 and the second part 196comprises an end ring 130 having a cross-section 132 configured as aC-channel 134. The cylinder 110 has a cylinder outer surface 116 and acylinder inner surface 114 defining a cylinder thickness 118. Inaddition, the cylinder 110 has a cylinder edge 120 which may beadhesively bonded within the C-channel 134. The end ring 130 may includea base 136 and a pair of flanges 138 defining the C-channel 134cross-section 132. One or both of the channel edges 144 may include achamfered edge 146 to minimize stress concentrations in the cylinder 110at the location of the channel edges 144. The end ring 130 may have achannel depth 142 corresponding to the bondline width 308 and extendingfrom the channel bottom surface 152 to the channel edge 144. Thedistance between the channel side surfaces (i.e., the channel side innersurface 148 and the channel side outer surface 150) may define a channelwidth 140.

In FIG. 3, the cylinder 110 may be positioned within the C-channel 134such that the gap 160 between the cylinder outer surface 116 and thechannel side outer surface 148 is substantially equalized with the gap158 between the cylinder inner surface 114 and channel side innersurface 148. In addition, the cylinder 110 may be positioned verticallyrelative to the end ring 130 such that the gap 156 between the channelbottom surface 152 and the cylinder edge surface 122 is substantiallyequalized with the gaps 158, 160 between the cylinder 110 and theflanges 138. The bonding process may include a means for maintaining theposition of the cylinder 110 relative to the end ring 130 such that thedesired gaps 156, 158, 160 are fixed (i.e., non-changing) during theinjection of structural adhesive 370 into the adhesive chambers 210(FIG. 2) and during curing of the structural adhesive 370.

In FIG. 4, shown is a flat pattern layout of the bonded joint 106between the end ring 130 and the cylinder 110 of FIG. 3. FIG. 4illustrates the relatively long bondline length 306 of the bondlineregion 300 between the end ring 130 and the cylinder edge 120. In anembodiment, the long length geometry feature 108 may be defined as abondline length 306 that is at least approximately twice the bondlinewidth 308 of the bonded joint 106. However, the bondline length 306 maybe less than the bondline width 308.

In FIG. 4, the bonded joint 106 advantageously includes a series ofchamber walls 212 spaced apart from one another along the bondlinelength 306 and dividing the bondline length 306 into a plurality ofadhesive chambers 210. In the embodiment shown, the chamber walls 212are oriented generally transverse to the bondline length 306. In thisregard, the chamber walls 212 may extend across the bondline width 308between opposing bondline edges 304 of the bondline region 300. Thechamber walls 212 may be oriented in non-parallel relation to thebondline length 306. For example, one or more of the chamber walls 212may be oriented generally perpendicular to the bondline length 306although the chamber walls 212 may be oriented in any direction relativeto the bondline length 306 and are not limited to a perpendicularorientation. Furthermore, although each one of the chamber walls 212 isshown as having a generally straight shape, the chamber walls 212 may beformed in any size, shape, and configuration, without limitation. Forexample, the chamber walls 212 may be curved or provided in other shapesor configurations.

As described in greater detail below, in FIG. 4, each one of theadhesive chambers 210 may be filled with structural adhesive 370 to bondthe mating surfaces 192, 198 of the first part 190 (e.g., the cylinder110) and the second part 196 (e.g., the end ring 130). A structuraladhesive may be selected that is compatible with the material of thefirst part 190 and the material of the second part 196. As indicatedabove, the first part 190 may be formed of a material that is differentthan the material of the second part 196. For example, the first part190 may comprise the cylinder 110 which may be formed offiber-reinforced polymer matrix material 124 such as a carbonfiber/epoxy matrix material. The second part 196 may comprise the endring 130 which may be formed of metallic material 162 such as aluminum.However, the first part 190 and the second part 196 may be formed of anymaterial, and may be of any shape, size, and configuration, withoutlimitation.

In FIG. 4, the structural adhesive 370 may be injected into each one ofthe adhesive chambers 210 through at least one injection port 312. In anembodiment, one or more injection ports 312 may be formed in the firstpart 190 and/or in the second part 196. However, injection ports 312 maybe formed at any location that allows for injection of structuraladhesive 370 into the adhesive chambers 210. For example, although notshown, one or more injection ports 312 may be located proximate orformed in the part edges 194, 200.

Referring to the flow chart of FIG. 23 with additional reference toFIGS. 5-22, the method 400 of forming a bonded joint 106 (FIG. 4) willnow be described. In the context of bonding the aft end ring 130 (FIG.5) to the cylinder 110 (FIG. 5), the end ring 130 may initially bedry-fitted to the cylinder 110 without structural adhesive 370 (FIG. 4)prior to initiating the bonding process. Dry-fitting may comprisepositioning the end ring 130 such that the C-channel 134 (FIG. 5) isfacing upwardly, and then lowering the cylinder 110 into the C-channel134 for checking and equalizing gaps 158, 160 (FIG. 3) between thechannel side inner and outer surfaces 148, 150 (FIG. 3) and the cylinderinner and outer surfaces 114, 116 (FIG. 3) around the cylindercircumference 112 (FIG. 2), and adjusting the gaps 156 (FIG. 3) betweenthe channel bottom surface 152 (FIG. 3) and the cylinder edge surface122 (FIG. 3). Pins (not shown) may be installed to fix the relativeposition of the cylinder 110 and the end ring 130. The gaps 156, 158,160 may be measured and recorded to establish the bondline thickness 310(FIG. 3) between the mating surfaces of the cylinder 110 and the endring 130. Once the gaps 156, 158, 160 are equalized or adjusted, thepins (not shown) may be removed and the cylinder 110 may be separatedfrom the end ring 130 to allow for cleaning of the mating surfaces suchas by solvent-wiping in preparation for bonding. Non-bonded surfaces(not shown) of the cylinder 110 and/or end ring 130 may be covered withmasking tape (not shown) or other material to protect against contactwith structural adhesive 370 (FIG. 3) during the bonding process.

Referring to FIG. 5, Step 402 of the method 400 (FIG. 23) may includeforming chamber walls 212 at predetermined spacing 224 (FIG. 4) from oneanother along the bondline length 306 (FIG. 4). In an embodiment, thechamber walls 212 may be located such that each adhesive chamber 210 hasa chamber length 216 (FIG. 4) that is the greater than the chamber width217 (FIG. 4). The chamber walls 212 may be formed using an adhesive 214that may be applied to a bond wire 230. The adhesive-coated bond wire230 may then be mounted to the first part 190 (e.g., the cylinder 110)prior to mating the first part 190 (e.g., the cylinder 110) with thesecond part 196 (e.g., the end ring 130). However, the presentdisclosure contemplates applying adhesive 214 to the first part (e.g.,the cylinder 110) without a bond wire 230. Alternatively, the adhesive214 may be applied to the second part 196 (e.g., the end ring 130)instead of the first part 190 to form the chamber walls 212. The methodmay include forming the chamber walls 212 generally transverse to thebondline length 306 (FIG. 4). The chamber walls 212 may be oriented innon-parallel relation to the bondline length 306 such as inperpendicular orientation to the bondline length 306. However, thechamber walls 212 may be formed in any configuration or shape thatdivides the bondline length 306 as indicated above.

In FIG. 5, Step 404 of the method 400 (FIG. 23) may comprise including abond wire 230 in one or more of the chamber walls 212. The bond wires230 may set the gap 154 (FIG. 3) or bondline thickness 310 (FIG. 3)between the mating surfaces 192, 198 and may assist as a barrier for theadhesive chamber 210. The method may include selecting a wire diameter234 based upon the desired gap 154 or bondline thickness 310 between themating surfaces. If bond wires 230 are not available in a wire diameter234 than matches the gap 154 (FIG. 3) size, then a wire diameter 234 maybe selected that is slightly smaller than the gap 154 size, and shims238 (FIG. 6) may be employed to assist in forming the desired gap 154(FIG. 3) between the mating surfaces 192, 198 as described below. Inaddition, the shim 238 may facilitate sealing the chamber wall 212adhesive 214 to the mating surfaces 192, 198, and shaping the sides ofthe chamber walls 212.

In FIG. 5, each one of the bond wires 230 may be pre-formed in a desiredshape such as in a U-shape to match the cylinder edge 120 and such thatthe bond wire 230 has free ends 232 that will extend upwardly beyond thechannel edge 144 when the cylinder 110 is installed in the C-channel134. The bond wires 230 may be cleaned such as by solvent wiping andadhesive 214 may be applied to the bond wires 230 such as by using asyringe (not shown). The method may include coating the bond wires 230with adhesive 214 with preferably no bare wire showing. The adhesive 214may be provided in a relatively high viscosity such as a paste-likeviscosity such that the adhesive 214 is retained on the bond wires 230.The bond wires 230 may be positioned against the surface of the firstpart 190 (i.e., the cylinder 110) at predetermined spacings 224 (FIG. 4)from one another such that the bond wires 230 divide the bondline length306 (FIG. 4). The method may include taping the free ends 232 of thebond wires 230 to the cylinder inner and outer surfaces 114, 116 withtape 236.

In FIG. 6, the method may include assembling the cylinder 110 (i.e., thefirst part 190) with the end ring 130 (i.e., the second part 196) byinserting the cylinder edge 120 into the C-channel 134. The process ofinstalling the bond wires 230, installing the adhesive 214, andassembling the cylinder 110 with the end ring 130, and shaping orfinalizing the chamber walls 214 is preferably completed within the potlife of the adhesive 214. The free ends 232 of each bond wire 230 may beheld in position using the tape 236 as shown. The cylinder 110 may bepinned in position using pins (not shown) for fixing the cylinder 110and end ring 130 in the same position determined during the dry-fittingprocess.

In FIG. 6, the method may include temporarily inserting a pair of shims238 within the bondline region 300 between the cylinder 110 and flanges138 of the end ring 130. The shims 238 may be fabricated at a shimthickness that corresponds to the gap 154 (FIG. 3) size or bondlinethickness 310 (FIG. 3) measurements from the dry-fitting process. Thebond wires 230 may be provided in a wire diameter 234 that substantiallymatches the desired gap 154 between the mating surfaces 192, 198 suchthat the bond wires set the bondline thickness 310 (FIG. 3) between themating surfaces 192, 198. If the bond wires 230 are not available in awire diameter 234 that matches the gap 154 size, then the next-smallestwire diameter may be used in the chamber walls and the shims 238 may beemployed to set the gap 154 size between the mating surfaces 192, 198.The shims 238 may be formed of any material including any metallic ornonmetallic material and may be covered or wrapped with a non-siliconematerial (not shown) such as Teflon™ tape (not shown) or other materialthat facilitates separation of the shims 238 from the chamber walls 212after the adhesive 214 has cured.

As shown in FIG. 6, the shims 238 may be positioned on opposite sides ofeach bond wire 230 at an initial spacing from one another. The methodmay include moving the shims 238 toward one another to a final spacingwherein the shim edges 240 may compact the adhesive 214 of the chamberwall 212 to seal the adhesive 214 to the mating surfaces 192, 198 andremove voids from the adhesive 214. In addition, the shims 238 mayprovide a defined (e.g., straight) edge to the chamber wall 212. Theshims 238 may be moved toward one another such that the shims edges 240are generally parallel to one another and spaced apart from one anotherat a distance corresponding to a desired width of the chamber walls 212.For example, the shims 238 may be moved toward one another at spacing ofapproximately 0.25 inch or at other spacing distances. In an alternativeembodiment, the chamber walls 212 may be formed without bond wires 230by inserting shims 238 into the bondline region 300 and then injectingadhesive 214 into a mold space (not shown) defined by the spacingbetween shim edges 240. Regardless of the manner in which the chamberwalls 212 are formed, the adhesive 214 in the chamber walls 212 may beallowed to cure prior to removing the shims 238 and prior to injectingstructural adhesive 370 (FIG. 3) into the adhesive chamber 210.

In FIG. 6, the bond wires 230 may be formed of any material and are notlimited to being formed of metallic wire. In addition, a chamber wall212 may be formed without the use of adhesive 214. For example, achamber wall 212 may be configured as a mechanical device (not shown)that may be fixedly positioned across the bondline width 308 in a mannerthat provides substantial sealing to an adhesive chamber 210. In afurther embodiment, as indicated above, bond wires 230 may be omittedfrom the chamber walls 212 and the adhesive 214 may be applied directlyto the exterior of the cylinder edge 120 prior to lowering the cylinder110 into the C-channel 134. Shims 238 may be positioned on oppositesides of the adhesive 214 and moved toward one another to form theadhesive 214 into chamber walls 212. The shims 238 may be removed priorto injection bonding of structural adhesive 370 (FIG. 3) into theadhesive chambers 210.

In FIG. 7, Step 406 of the method 400 (FIG. 23) may comprise forming oneor more bondline dams 314 along one or more bondline edges 304 of thebondline region 300. One or more of the bondline dams 314 may be formedof a relatively high-viscosity adhesive 316 or other material having thecapability to adhere to the cylinder 110 and the end ring 130 andremains in position during the bonding process and resist the pressureof the structural adhesive 370 (FIG. 3) during injection thereof intothe adhesive chamber 210. In an embodiment, the bondline dams 314 may beformed of an adhesive 316 having a higher viscosity that the viscosityof the structural adhesive 370 that is injected into the adhesivechamber 210. The bondline dams 314 may be formed along a part edge 194,200 of the first part 190 (e.g., the cylinder 110) and/or the secondpart 196 (e.g., end ring 130) being bonded together.

In FIG. 7, bondline dams 314 may be formed along the upper channel edges144 of the end ring 130 on both sides of the cylinder 110. One or moreof the bondline dams 314 may terminate at a spaced distance from thechamber walls 212 to form a bleed hole 330 for the discharge of excessadhesive 336 (FIG. 12) from the adhesive chamber 210. In an embodiment,each bleed hole 330 may be located proximate an upper edge 220 of theadhesive chamber 210. In addition, each bleed hole 330 may be locatedproximate a chamber wall 212. Positioning of the bleed holes 330 alongthe upper edge 220 of the adhesive chamber 210 and proximate the chamberwalls 212 may facilitate the evacuation of air bubbles 382 (FIG. 11)from the adhesive chamber 210 during the injection of structuraladhesive 370 (FIG. 11). However, the bleed holes 330 may be located atany position on the adhesive chamber 210. In an embodiment, one or moreof the adhesive chambers 210 may include a large bleed hole 334 and asmall bleed hole 332 located at opposing chambers ends 218 of theadhesive chamber 210. The large bleed hole 334 and the small bleed hole332 may be formed in any size, without limitation. As described ingreater detail below, the arrangement of the large bleed hole 334 andthe small bleed hole 332 may facilitate the evacuation of air bubbles382 from the adhesive chamber 210.

In FIG. 7, the configuration of the bondline dam 314 and the bleed holes330 on the cylinder inner surface (not shown) may be similar to theconfiguration of the bondline dam 314 and the bleed holes 330 on thecylinder outer surface 116. However, the configuration of the bondlinedam 314 and the bleed holes 330 on each side of the cylinder 110 may bedifferent. The bondline dams 314 and the chamber walls 212 may define atleast a portion of the bondline perimeter 302. The chamber walls 212,the bondline dams 314, and the mating surfaces 192, 198 may collectivelyenclose the adhesive chambers 210. The bondline dams 314 may be formedfrom adhesive 316 such as by using a syringe (not shown). The method mayinclude allowing the adhesive 316 of the bondline dam 314 to cure priorto injecting structural adhesive 370 (FIG. 11) into the adhesive chamber210. Although the bondline dams 314 are described as being formed ofadhesive 316, it is contemplated that the bondline dams 314 may comprisea mechanical device (not shown) such as a rigid member that may bemechanically coupled or otherwise attached to the first part 190 and/orsecond part 196 along the bondline perimeter 302.

In FIG. 8, the method may include forming one or more adhesivereservoirs 350 for collecting excess adhesive 336 (FIG. 12) that may bedischarged from the bleed holes 330 during injection of the structuraladhesive 370 (FIG. 12) into the adhesive chambers 210. In an embodiment,one or more of the adhesive reservoirs 350 may be formed as a shelf 354that extends laterally outwardly from the cylinder 110 and/or from theend ring 130. The adhesive reservoirs 350 may collect excess adhesive(not shown) that may flow outwardly as a pool onto the shelf 354 duringthe discharge of excess adhesive 336 from the bleed holes 330. The shelf354 may be configured to collect the excess adhesive 336 and/or preventthe excess adhesive 336 from flowing onto the exterior of the structuralassembly 104. The shelf 354 may be formed of non-silicone material suchas polymeric tape or sheeting and/or chromate tape or other materialthat may be applied to the end ring 130 and/or cylinder 110. In anembodiment, each adhesive chamber 210 may include a dedicated shelf 354that may be physically separated from the dedicated shelf 354 of theadjacent adhesive chamber 210 such that each shelf 354 contains theexcess adhesive 336 discharged from the corresponding adhesive chamber210.

In FIG. 9, one or more of the adhesive reservoirs 350 may be formed as avertical tube or vertical column 352 that may be fluidly coupled to ableed hole 330. In an embodiment, each one of the vertical columns 352may be releasably attached to the cylinder 110 such as by using adhesivetape (not shown). In an embodiment, the vertical columns 352 may beformed of non-silicone polymeric material (not shown) to avoidcontamination of the structural adhesive 370 (FIG. 12). The material forforming the vertical columns 352 may be at least partially opticallytransparent material 356 to facilitate the observation of the flow ofexcess adhesive 336 (FIG. 12) into the vertical columns 352 during thedischarge thereof from the bleed hole 330.

FIG. 10 illustrates a large bleed hole 334 and a small bleed hole 332located on opposite chamber ends 218 of each adhesive chamber 210. In anembodiment, the large bleed hole 334 may have a width in the range offrom approximately 0.12-1.0 inch long or longer. For example, the largebleed hole may be approximately 0.50 inch long. The small bleed hole 332may have a width in the range of from approximately 0.12-50 inch long orlonger. For example, the small bleed hole 332 may be approximately 0.25inch long. Each bleed hole 332, 334 may be located proximate a chamberwall 212. In addition, each bleed hole 332, 334 may be formed along abondline dam 314 or at a terminal end of a bondline dam 314 along theupper channel edge 144 of the end ring 130.

In the embodiment shown in FIG. 10, an injection port 312 may be locatedproximate the chamber end 218 where the small bleed hole 332 may belocated. The injection port 312 may be located proximate the lower edge222 of the adhesive chamber 210 such as along the channel bottom surface152 (FIG. 9). As described below, by locating the injection port 312 onthe chamber end 218 having the small bleed hole 332, air bubbles 382inside the adhesive chamber 210 may initially evacuate through the smallbleed hole 332 and the large bleed hole 334 when structural adhesive 370(FIG. 11) is initially injected into the adhesive chamber 210. Afterstructural adhesive 370 starts to discharge through the small bleed hole332, air bubbles 382 (FIG. 11) may continue to evacuate through thelarge bleed hole 334. In this regard, by positioning the injection port312 proximate the chamber end 218 having the small bleed hole 332, airbubbles 382 may be evacuated along a substantial entirety of the chamberlength 216 from one chamber end 218 to an opposite chamber end 218 andwhich may result in a reduced propensity for void formation or airbubble 382 (FIG. 11) entrapment along the upper bondline perimeter 302.

Referring to FIG. 11, Step 408 of the method 400 (FIG. 23) may includeinjecting the structural adhesive 370 into the adhesive chamber 210.FIG. 11 illustrates the flow direction 380 of the structural adhesive370 and the air bubbles 382 within the adhesive chamber 210. Thestructural adhesive 370 may be injected under an injection pressure 372by using an injection device 374 such as a sealant gun or adhesive gunor similar device coupled to an air pressure source 378 such as with anair hose 376. The structural adhesive 370 may be injected into theadhesive chamber 210 at an injection pressure 372 of betweenapproximately 0.5-100 pounds per square inch (psi) or greater. Forexample, the structural adhesive 370 may be injected at an injectionpressure 372 of between approximately 20-100 pounds per square inch(psi) such as approximately 50 psi. The selection of the injectionpressure 372 may be dependent upon various parameters including, but notlimited to, bondline thickness 310 (FIG. 3), cross-sectionalconfiguration of the bonded joint 106 such as the C-channel 134cross-sectional configuration (FIG. 13) versus a straight-linecross-sectional configuration (FIG. 21), viscosity and temperature ofthe structural adhesive 370, adhesive chamber 210 geometry anddimensions including chamber length 216, chamber width 217, bondlinethickness 310, and other parameters.

In FIG. 11, in an embodiment, the structural adhesive 370 may initiallycomprise a liquid or semi-liquid material configured to be injected intothe adhesive chambers 210. The structural adhesive 370 may comprise aone-part adhesive or a multi-part adhesive. In an embodiment, thestructural adhesive 370 may comprise epoxy adhesive. The adhesivecomposition may be selected based on the material composition of themating parts. The structural adhesive 370 may have a viscosity thatfacilitates injection into the adhesive chambers 210. The viscosity maybe selected based on the bondline thickness 310 (FIG. 3) such that thestructural adhesive 370 flows through the gaps 156, 158, 160 (FIG. 3)between the mating surfaces 192, 198 (FIG. 3) to substantially fill theadhesive chamber 210 in a manner that promotes the evacuation of airbubbles 382 and which minimizes or eliminates void formation. In anembodiment, the structural adhesive 370 may comprise a thixotropicmaterial having an initially low viscosity to facilitate the flow of thestructural adhesive 370 into the adhesive chamber 210 and through therelatively narrow bondline thickness 310 of the adhesive chamber 210.After injection, the structural adhesive 370 may increase in viscosityor thicken over time such as after the adhesive chambers 210 are filledand plugged and/or during curing of the structural adhesive 370.

In FIG. 12, Step 410 of the method 400 (FIG. 23) may include evacuatingair bubbles 382 from the adhesive chamber 210 through one or more of thebleed holes 330 that may be fluidly coupled to the adhesive chamber 210.In FIG. 12, shown is the adhesive chamber 210 nearing a filled state 384(FIG. 17) and illustrating the flow of the structural adhesive 370 andair bubbles 382 toward the large bleed hole 334. In FIG. 12, by locatingthe injection port 312 proximate a lower edge 222 of the adhesivechamber 210, air bubbles 382 will advantageously migrate upwardly towardthe bleed holes 330. For embodiments having a small bleed hole 332 and alarge bleed hole 334, the injection port 312 may advantageously belocated underneath the small bleed hole 332 which may promote theevacuation of air bubbles 382 along the flow direction 380 from onechamber end 218 to an opposite chamber end 218 due to the tendency ofair bubbles 382 to move along the path of least resistance presented bythe large bleed hole 334.

In FIG. 12, Step 412 of the method 400 (FIG. 23) may include dischargingexcess adhesive 336 through one or more of the bleed holes 330. FIG. 12shows the discharge of excess adhesive 336 through the small bleed hole332 and into the adhesive reservoir 350 during the injection of thestructural adhesive 370 into the adhesive chamber 210. The discharge ofexcess adhesive 336 may occur simultaneous with the evacuation of airbubbles 382 from the adhesive chamber 210. As indicated above, the bleedholes 330 may be formed at a bondline perimeter 302 such as along thebondline dam 314. Although not shown, one or more bleed holes 330 mayalso be formed in the first part 190 and/or in the second part 196 of astructural assembly 104 as an alternative to forming bleed holes 330along a bondline dam 314.

In FIG. 13, shown is a cross-sectional view illustrating the injectionof the structural adhesive 370 into the adhesive chamber 210 through aninjection port 312. The injection port 312 may be countersunk forseating a nozzle (not shown) of the injection device 374. For theC-channel 134 configuration shown in FIG. 13, the structural adhesive370 may be injected into an injection port 312 located on one side ofthe C-channel 134 such that the structural adhesive 370 flows along theindicated flow direction 380 upwardly along the cylinder outer surface116 toward the bondline dam 314 at the channel edge 144. The structuraladhesive 370 may also flow through the gap 154 between the channelbottom surface 152 and the cylinder edge 120 and then upwardly along theflow direction 380 into the gap 154 between the channel side surface 148and the cylinder inner surface 114 on a side of the C-channel 134opposite the injection port 312 and toward the bondline dam 314 whereinexcess adhesive 336 may be discharged into one or more adhesivereservoirs located along the cylinder inner surface 114.

In FIG. 14, Step 414 of the method 400 (FIG. 23) may include collectingexcess adhesive 336 with the adhesive reservoirs 350 that are fluidlycoupled to the bleed holes 330. In FIG. 14, shown is an adhesive chamber210 in a filled state 384 with excess adhesive 336 collected within theadhesive reservoirs 350. On an opposite side (not shown) of the cylinder110, a similar set of bleed holes 330 and adhesive reservoirs 350 may beprovided for collecting excess adhesive 336. In the bonded joint 106 ofFIG. 14, the bleed holes 330 and the injection port 312 may bepositioned such that the structural adhesive 370 flows upwardly towardthe bondline dam 314 at the upper channel edge 144. The structuraladhesive 370 remains at the upper channel edge 144 while the adhesivechamber 210 is filled allowing the structural adhesive 370 to flow alongthe upper channel edge 144 toward the bleed holes 330 and into theadhesive reservoirs 350 fluidly coupled to the adhesive chamber 210. Theinjection of structural adhesive 370 into the adhesive chamber 210 maycontinue until a predetermined amount of excess adhesive 336 iscollected in each one of the adhesive reservoirs 350. During theinjection of the structural adhesive 370, a technician may be stationedon each side (i.e., on the inner side and on the outer side) of thecylinder 110 to visually verify that each adhesive reservoir 350contains excess adhesive 336 which may indicate that the adhesivechamber 210 is completely filled.

In FIG. 15, shown is the injection of the structural adhesive 370 intoanother adhesive chamber 210 located proximate a recently-filledadhesive chamber 210. In FIG. 15, the bonded joint 106 includes a seriesof the adhesive chambers 210 disposed along the bondline length 306. Theseries of adhesive chambers 210 may be filled in succession, or theadhesive chambers 210 may be filled in an alternative filling sequence.Structural adhesive 370 may be injected into each adhesive chamber 210until the adhesive reservoirs 350 for each adhesive chamber 210 arefilled. By filling the adhesive reservoirs 350 to a level that is abovethe level of the bleed holes 330, the adhesive reservoirs 350 mayprovide positive pressure to the adhesive chambers 210 to prevent theentrance of air into the adhesive chamber 210.

In FIG. 16, Step 416 of the method 400 (FIG. 23) may include pluggingeach injection port 312 with a plug 386 after filling the adhesivechamber 210 and removing the injection device 374 from the injectionport 312. Adhesive residue (not shown) may be wiped from the exterior ofthe injection port 312 prior to installation of the plug 386. The plug386 may trap the structural adhesive 370 within the adhesive chamber 210and prevent the leakage of structural adhesive 370. The plug 386 may besized and configured to provide a relatively tight fit with theinjection port 312. The plug 386 may be formed of a metallic material orany other material that can be separated from the structural adhesive370 and removed from the injection port 312 after the structuraladhesive 370 is cured.

In FIG. 17, shown is a portion of the bonded joint 106 between thecylinder 110 and the end ring 130 and illustrating each one of theadhesive chambers 210 filled with structural adhesive 370. Excessadhesive 336 is contained within each one of the adhesive reservoirs350. Plugs 386 are shown installed in each one of the injection ports312. As indicated earlier, the adhesive reservoirs 350 may beconstructed of substantially optically transparent material to allowvisual observation of the level of excess adhesive 336 as confirmationthat the adhesive chambers 210 are filled.

In FIG. 18, Step 418 of the method 400 (FIG. 23) may include allowingthe structural adhesive 370 within the adhesive chamber 210 to cure fora predetermined period of time. Heat (not shown) may optionally beapplied to the bonded joint 106 to facilitate the curing of thestructural adhesive 370. Following the curing of the structural adhesive370, the bondline dams 314 (FIG. 17) and the adhesive reservoirs 350(FIG. 17) may be removed from the bonded joint 106. Protruding bondwires 230 may be trimmed. Adhesive residue (not shown) may be removedfrom the bonded joint 106. Optionally, one or more mechanical fasteners388 may be installed as shown. For example, a mechanical fastener 388may be installed through the adhesive chambers 210 to increase thestrength of the bonded joint 106 and/or to prevent peeling forcesbetween the cylinder 110 and the flanges 138 of the end ring 130.

In FIG. 19, shown is an embodiment of a bonded joint 106 between anexternal ring 172 and the cylinder 110 of the structural assembly 104 ofFIG. 2. As indicated above, the cylinder 110 may be formed of afiber-reinforced polymer matrix material 124 such as a carbon fiberepoxy material or other composite material. The external ring 172 may beformed of a metallic material 162 such as aluminum. The external ring172 may have a ring upper edge 174 and a ring lower edge 176. Theexternal ring 172 may be fixed in position relative to the cylinder 110to provide a predetermined bondline thickness 310 around a cylindercircumference 112 (FIG. 2). The bondline thickness 310 may beestablished during a dry-fit operation similar to the dry-fit operationdescribed above for the bonded joint 106 shown in FIG. 3.

In FIG. 19, the bondline thickness 310 between the external ring 172 andthe cylinder 110 may be established using a series of bond wires 230(FIG. 6) positioned around the cylinder circumference 112. The bondwires 230 may be positioned at predetermined spacings 224 (FIG. 2) fromone another. Although not shown, such bond wires may have a generallystraight configuration and may be installed in a manner similar to thebond wire 230 (FIG. 5) installation described above with regard to theC-channel 134 (FIG. 5) end ring 130 shown in FIG. 5. In FIG. 19, thecylinder 110 may be installed within the external ring 172 and theexternal ring 172 may be pinned in position relative to the cylinder110. Shims (not shown) may be inserted into the bondline region 300 toshape each chamber wall 212 (FIG. 20) in a manner described above. Theshims may be removed after forming the chamber walls 212 and prior tothe injection of structural adhesive 370 into the adhesive chambers 210(FIG. 20).

In an alternative embodiment, in FIG. 19, the chamber walls 212 may beformed without the use of bond wires 230 (FIG. 20). For example, a pairof shims 238 (FIG. 6) may be inserted within the bondline region 300 toestablish the gap 154 (FIG. 3) between the mating surfaces 192, 198.Adhesive 214 (FIG. 20) may be injected into the space between the shims238 to form the chamber walls 214. The shims 238 may be moved toward oneanother in a manner as shown in FIG. 6 to shape the edges of the chamberwalls 212 and to define a width of the chamber walls 212 and to seal theadhesive 214 against the mating surfaces 192, 198. The shims 238 may beremoved from the bondline region 300 following the curing of theadhesive 214 of the chamber walls 212.

In FIG. 20, shown is a flat pattern layout of the bonded joint 106 ofFIG. 19 during a bonding process wherein structural adhesive 370 may beinjected into an injection port 312 of one of the adhesive chambers 210.The adhesive chambers 210 are separated from one another by the chamberwalls 212. One or more adhesive reservoirs 350 may be formed to collectexcess adhesive 336 from the adhesive chambers 210. The adhesivereservoirs 350 may be configured as vertical columns 352 as describedabove and may be formed of at least partially optically transparentnon-silicone polymeric material 356 or other material that facilitatesthe observation of excess adhesive 336 discharging from the adhesivechambers 210. However, the adhesive reservoirs 350 may be provided inany one of a variety of alternative configurations for collecting excessadhesive 336 discharged from the bleed holes 330. For example, theadhesive reservoirs 350 may be formed as shelves 354 (FIG. 8).

In FIG. 21, shown is a sectional view of the external ring 172 andcylinder 110 and illustrating the bondline dams 314 that may be formedalong the ring upper edge 174 and/or the ring lower edge 176. Thebondline dams 314 may define the bondline perimeter 302 enclosing theadhesive chamber 210. Bleed holes 330 (FIG. 20) may be formed along thering upper edge 174 and/or ring lower edge 176 in a manner describedabove. An injection device 374 may be seated in the injection port 312for injecting the structural adhesive 370 into the adhesive chamber 210.

In FIGS. 20-21, the injection ports 312 may be positioned approximatelyat a geometric center 318 (e.g., vertical center and/or horizontalcenter) of the adhesive chamber 210 to facilitate the uniformdistribution and flow of the structural adhesive 370 from the injectionport 312 toward the bondline perimeters 302. During the injectionprocess, air bubbles 382 (FIG. 20) may evacuate from the adhesivechamber 210 through the bleed holes 330. Although the bleed holes 330 inFIG. 20 are shown as being located along the ring upper edge 174 for thevertically-oriented bondline region 300, it is contemplated that forarrangements where the bondline region 300 is generallyhorizontally-oriented (not shown), bleed holes 330 may be included onopposite edges of the external ring 172 such as along the same edges asthe bondline dams 314 in FIG. 21.

In FIG. 22, shown is the bonded joint 106 of FIG. 20 in a final statefollowing the curing of the structural adhesive 370 in the adhesivechambers 210 and the removal of the adhesive reservoirs 350 (FIG. 20),the bondline dams 314, and plugs (not shown). Also shown is the optionalinstallation of mechanical fasteners 388 such as threaded fasteners(e.g., bolts, Hi-loks™, rivets, etc.) through each one of the adhesivechambers 210 to increase the strength of the bonded joint 106 and/or tominimize peeling forces. The process of bonding an internal ring 170(FIG. 2) to the cylinder 110 may be performed in a manner similar to theabove-described process of bonding the external ring 172 to the cylinder110.

FIG. 24 is a block diagram of a bonded joint 106 illustrating the matingsurface 192 of a first part 190 bonded to the mating surface 198 of asecond part 196. The first part 190 and the second part 196 maycollectively form the structural assembly 104. The mating surfaces 192,198 may be bonded together along a bondline region 300 having a bondlinelength 306 and a bondline width 308. In an embodiment, the bonded joint106 may comprise a long length geometry feature 108 (FIG. 2). Forexample, the bondline length 306 may be at least twice as long as thebondline width 308.

In FIG. 24, in an embodiment, the first part 190 and the second part 196may define a substantially straight, planar bondline region 300 as isschematically shown in FIG. 5, and are not limited to a curved panel ora cylinder 110 bonded to a ring such as an end ring 130 or internal orexternal ring 170, 172 as shown in FIG. 2. In this regard, the firstpart 190 and the second part 196 may define a relatively long, straight,generally planar bondline region 300 having a generally straight-linecross-sectional configuration (e.g., FIG. 21). The bondline length 306may be twice the bondline width 308 or larger. For example, the bondlinelength 306 of such straight, planar bondline region 3600 may be three(3) or more times the bondline width 308 or longer.

In FIG. 24, the bondline length 306 may be divided by a series ofchamber walls 212 that may be formed within the bondline region 300between the mating surface 192 of the first part 190 and the matingsurface 198 of the second part 196. In an embodiment, the chamber walls212 may be oriented generally transverse to the bondline length 306although other orientations of the chamber walls 212 are contemplated.One or more of the chamber walls 212 may include a bond wire 230 forsetting a gap (not shown) between the mating surfaces 192, 198. At leastone bondline dam 314 (FIG. 17) may be formed along a part edge 194, 200(FIG. 13) of least one of the first part 190 and the second part 196 todefine at least a portion of the bondline perimeter 302 (FIG. 17). Thechamber wall(s) 212, the bondline dam(s) 314, and the mating surfaces192, 198 may collectively enclose the adhesive chamber(s) 210.

In FIG. 24, one or more bleed holes 330 may be formed along the bondlinedam 314 (FIG. 17) or along other locations of the bondline region 300.The bleed hole(s) 330 may allow for the discharge of excess adhesive 336(FIG. 12) from the adhesive chambers 210. One or more adhesivereservoirs 350 may be fluidly coupled to the bleed holes 330 to collectexcess adhesive 336 discharged from the adhesive chambers 210 duringinjection of structural adhesive 370 into the adhesive chambers 210. Thestructural adhesive 370 may be injected into the adhesive chamber 210through an injection port 312 after the adhesive chamber 210 is sealedand/or enclosed along the chamber walls 212 and the bondline dams 314.

Referring to FIGS. 25-26, embodiments of the disclosure may be describedin the context of an aircraft manufacturing and service method 500 asshown in FIG. 25 and an aircraft 502 as shown in FIG. 26. Duringpre-production, exemplary method 500 may include specification anddesign 504 of the aircraft 502 and material procurement 506. Duringproduction, component and subassembly manufacturing 508 and systemintegration 510 of the aircraft 502 takes place. Thereafter, theaircraft 502 may go through certification and delivery 512 in order tobe placed in service 514. While in service by a customer, the aircraft502 is scheduled for routine maintenance and service 516 (which may alsoinclude modification, reconfiguration, refurbishment, and so on).

Each of the processes of method 500 may be performed or carried out by asystem integrator, a third party, and/or an operator (e.g., a customer).For the purposes of this description, a system integrator may includewithout limitation any number of aircraft manufacturers and major-systemsubcontractors; a third party may include without limitation any numberof venders, subcontractors, and suppliers; and an operator may be anairline, leasing company, military entity, service organization, and soon.

As shown in FIG. 26, the aircraft 502 produced by exemplary method 500may include an airframe 518 with a plurality of systems 520 and aninterior 522. Examples of high-level systems 520 include one or more ofa propulsion system 524, an electrical system 526, a hydraulic system528, and an environmental system 530. Any number of other systems may beincluded. Although an aerospace example is shown, the principles of theinvention may be applied to other industries, such as the automotiveindustry.

Apparatus and methods embodied herein may be employed during any one ormore of the stages of the production and service method 500. Forexample, components or subassemblies corresponding to production process508 may be fabricated or manufactured in a manner similar to componentsor subassemblies produced while the aircraft 502 is in service. Also,one or more apparatus embodiments, method embodiments, or a combinationthereof may be utilized during the production stages 508 and 510, forexample, by substantially expediting assembly of or reducing the cost ofan aircraft 502. Similarly, one or more of apparatus embodiments, methodembodiments, or a combination thereof may be utilized while the aircraft502 is in service, for example and without limitation, to maintenanceand service 516.

Additional modifications and improvements of the present disclosure maybe apparent to those of ordinary skill in the art. Thus, the particularcombination of parts described and illustrated herein is intended torepresent only certain embodiments of the present disclosure and is notintended to serve as limitations of alternative embodiments or deviceswithin the spirit and scope of the disclosure.

What is claimed is:
 1. A method of forming an injection-bonded joint,comprising the steps of: providing a first part having opposing innerand outer surfaces, and a second part having a cross-section comprisinga C-channel; inserting a circumferential or planar edge of the firstpart into the C-channel; forming a chamber wall within a bondline regionbetween mating opposing surfaces of the first part and the C-channel ofthe second part, the chamber wall dividing a bondline length anddefining at least one adhesive chamber; forming a bondline dam along anupper edge of the C-channel on each opposing inner and outer surface ofthe first part, the chamber wall, the bondline dam, and the matingsurfaces collectively enclosing the adhesive chamber; injecting astructural adhesive into each adhesive chamber through an injection portformed in the second part; discharging excess structural adhesive fromeach adhesive chamber through a bleed hole located between the first andsecond parts and formed within the bondline dam of the adhesive chamber;and collecting the excess structural adhesive in an adhesive reservoirfluidly coupled to each bleed hole, each adhesive reservoir being formedas one of a vertical column comprising a longitudinally-extendingchannel attached to the outer surface of the first part and an outwardlyprojecting shelf attached to an outer surface of the second part.
 2. Themethod of claim 1, wherein the step of forming the chamber wallcomprises: forming the chamber wall from adhesive.
 3. The method ofclaim 1, wherein the step of forming the chamber wall comprises:including a bond wire in the chamber wall.
 4. The method of claim 1,wherein the bondline length is at least twice a bondline width.
 5. Themethod of claim 1, wherein the injection port is located proximate achamber wall.
 6. The method of claim 1, wherein the injection port islocated proximate a lower edge of the adhesive chamber.
 7. The method ofclaim 1, wherein the bleed hole and the injection port are located atopposite chamber ends of the adhesive chamber.
 8. The method of claim 1,wherein: a large bleed hole and a small bleed hole are located atopposing chambers ends of the adhesive chamber; and the injection portbeing located proximate a chamber end having the small bleed hole. 9.The method of claim 1, wherein the first part comprises a cylinder, thesecond part comprising an end ring having a cross-section configured asa C-channel, the step of forming the chamber wall comprising: attachinga series of bond wires along a cylinder edge such that the bond wiresdivide the bondline length; coating the bond wires with chamber walladhesive; and inserting a cylinder edge into the C-channel.
 10. A methodof forming an injection-bonded joint, comprising the steps of: providinga first part having opposing inner and outer surfaces, and a second parthaving a cross-section comprising a C-channel; inserting acircumferential or planar edge of the first part into the C-channel;forming a series of chamber walls between mating opposing surfaces ofthe first part and the C-channel of the second part, the chamber wallsdividing a bondline length into a plurality of adhesive chambers;forming bondline dams along an upper edge of the C-channel on eachopposing inner and outer surface of the first part, the chamber walls,the bondline dams, and the mating surfaces collectively enclosing theadhesive chambers; injecting a structural adhesive into each of theadhesive chambers through an injection port formed in the second part;discharging excess structural adhesive from each of the adhesivechambers through at least one bleed hole located in the bondline damsbetween the first and second part at a bondline perimeter of theadhesive chamber; and collecting the excess structural adhesive inadhesive reservoirs fluidly coupled to the bleed holes, each adhesivereservoir being formed as one of a vertical column comprising alongitudinally-extending channel attached to the outer surface of thefirst part and an outwardly projecting shelf attached to an outersurface of the second part.
 11. A structural assembly, comprising: afirst part having opposing inner and outer surfaces, and a second parthaving a cross-section comprising a C-channel, a circumferential orplanar edge of the first part being inserted into the C-channel, andopposing mating surfaces of the first part and the C-channel of thesecond part being adhesively bonded together along a bondline regionhaving a bondline length; a series of chamber walls formed along thebondline length and dividing the bondline length into a plurality ofadhesive chambers; a bondline dam formed along an upper edge of theC-channel on each opposing inner and outer surface of the first part,the chamber wall, the bondline dam, and the mating surfaces collectivelyenclosing the adhesive chambers; a structural adhesive injected into theadhesive chambers through at least one injection port formed in thesecond part, and excess structural adhesive being discharged from ableed hole located between the first and second parts and formed withinthe bondline dam of each of the adhesive chambers; and a plurality ofadhesive reservoirs, each attached to an outer surface of one of thefirst and second parts and fluidly coupled to a respective one of thebleed holes for collecting the excess structural adhesive, each adhesivereservoir being formed as one of a vertical column comprising alongitudinally-extending channel attached to the outer surface of thefirst part and an outwardly projecting shelf attached to an outersurface of the second part.
 12. The structural assembly of claim 11,wherein: the chamber walls are oriented generally transverse to thebondline length.
 13. The structural assembly of claim 11, furthercomprising: a bond wire included with at least one of the chamber walls.14. The structural assembly of claim 13, wherein: the bond wire definesa bondline thickness between the mating surfaces.
 15. The structuralassembly of claim 11, wherein: the structural adhesive comprises anepoxy adhesive.
 16. The structural assembly of claim 11, furthercomprising: at least one mechanical fastener extending through the firstpart and the second part in the bondline region.
 17. The structuralassembly of claim 11, wherein: the first part and the second part definea substantially straight, planar bondline region.
 18. The structuralassembly of claim 11, wherein: the first part comprises a cylinderhaving a cylinder edge; the second part comprising an end ring having across-section configured as a C-channel; and the series of chamber wallsbeing distributed around a cylinder circumference to form the pluralityof the adhesive chambers bonding the cylinder edge to the C-channel. 19.The structural assembly of claim 11, wherein: the first part is formedof fiber-reinforced polymer matrix material; and the second part isformed of metallic material.
 20. The structural assembly of claim 11,wherein the bondline length is at least twice a bondline width.